Sheet clamping couple



NOV- 4, 1969 D s. AGRls'rA ETAL 3,476,377

SHEET CLAMPING COUPLE Filed Oct. 19, 1967 United States Patent O 3,476,377 SHEET CLAMPING COUPLE Dominic S. Agrista and Anthony S. Anastasia, South Plainfield, NJ., assignors to Mattel, Inc., Hawthorne,

Calif., a corporation of California Filed Oct. 19, 1967, Ser. No. 676,449 Int. Cl. B25b 11/00 U.S. Cl. 269-21 7 Claims ABSTRACT F THE DISCLOSURE A pneumatic sheet-clamping couple includes a piston carried by one clamping frame and a cylinder carried by the other frame. The piston engages the cylinder when the frames are in clamping position and a vacuum pump evacuates the cylinder so that atmospheric pressure on the piston exerts suflicient force to hold the frames in clamping relationship.

BACKGROUND OF THE INVENTION The background of the invention will be set forth in two parts:

Field of the invention The invention pertains generally to the field of clamping couples and more particularly to a new and useful pneumatic sheet-clamping couple wherein a piston in an evacuated cylinder holds a pair of clamping frames together.

Description of the prior art In certain types of molding operations, a plastic sheet is held between clamping frames while the sheet is softened and then subjected to a vacuum for drawing the softened sheet into engagement with a suitable die. Mechanicalclamping couples may be employed for maintaining the frames in firm engagement with the edges of the sheet during this drawing operation.

Mechanical clamping couples have the disadvantage that comparatively large amounts of energy and time are required to clamp and unclamp the frames.

SUMMARY OF THE INVENTION In view of the foregoing, it is a primary object of the present invention to provide a new and useful sheet clamping'couple which automatically holds a pair of clamping frames together when the frames are swung into clamping engagement with each other.

Another object of the present invention is to provide a new and useful. clamping couple of the type described which includes a vacuum-actuated clamping member for holding clamping frames together in clamping engagement.

A further object of the present invention is to provide a new and useful vacuum-actuated clamping couple havinga piston which is automatically engaged in a cylinder when sheet clamping frames are brought together and having means for automatically evacuating the cylinder when the piston comes to rest therein.

According to the present invention, a new and useful sheet-clamping couple is provided and includes first and second clamping frames between which a sheet may be firmly held by its edges. The frames are connected together by a hinge so that the frames may be swung from an open to a closed position to clamp a sheet therebetween. A piston and a swingable nger are attached to one of the frames. The piston becomes engaged in a cylinder attahed to the other frame and the finger engages a valve when the frames are closed. The valve controls the flow of air from the cylinder to a vacuum pump and is automatically opened by the swingable finger whereby the cylinder will be automatically evacuated when the frames are closed. Atmospheric pressure on the piston maintains the frames in clamping position.

The piston may be released at the end of a clamping operationby swinging the finger out of engagement with the valve which then automatically vents the cylinder to atmosphere.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanying drawings in which like reference characters refer to like elements in the several views.

BRIEF DESCRIPTION OF THE DRAWING FIGURE 1 is a perspective View of a sheet-clamping couple constituting a presently preferred embodiment of the invention;

FIGURE 2 is an enlarged, partial cross-sectional view taken along line 2 2 of FIGURE 1; and

FIGURE 3 is an enlarged, partial cross-sectional view taken along line 3-3 of FIGURE 1.

DESCRIPTION `OF THE PREFERRED EMBODIMENT Referring again to the drawing, a sheet-clamping couple constituting a presently preferred embodiment of the invention, generally designated 10, is shown herein for purposes of illustration, but not of limitation, as forming part of a vacuum molding fixture 12.

The fixture 12 includes a base portion 14 having a bottom wall 16, and encompassing side wall 18 and an open top 20. The open top 20 is surrounded by a flange means 22 which is overlain by a resilient frame 24 for supporting a plastic sheet 26 which may be heat-softened and drawn into base portion 14 through open top 20 and into firm engagement with bottom wall 16 and side wall 18 to be molded into the shape represented thereby. The sheet 26 includes a peripheral edge portion 28 which must be firmly clamped during this drawing operation.

This clamping may be accomplished by closing a clamping frame 30 on a second clamping frame comprising the flange 22 and the pad 24.

The clamping frame 30 is hingedly connected to the flange 22 by a piano hinge 32 and includes an inturned flange 34 adapted to overlie peripheral edge 28 of sheet 26 and resilient pad 24.

The clamping frame 30 may be maintained in clamping relationship with the base portion 14 by a vacuum-actuated clamp 36 which includes a piston assembly 38 and a cylinder or cup 40. The piston assembly 38 is affixed to the clamping frame 30y by an L-shaped bracket 42 having a long leg 44 and a short leg 46. The short leg 46 may be connected to clamping frame 30 by suitable bolt and nut assemblies, like the one shown at 50 in FIGURE 2. The long leg 44 is provided with an aperture 52 receiving the piston assembly 38 which includes an adjustable stem 54 having a first end 56, an intermediate portion 58 and a second end 60. The piston assembly 38 also includes a flat, disc-like piston 62 which is aflixed to end 56 of stern 54 and which includes flat upper and lower faces 64, 66, respectively. The end 60 of stem 54 is externally threaded and carries a handgrip member 68 which may be grasped to swing clamping frame 30 with respect to base portion 14. An adjusting nut 70 threadedly engages end 60` and includes a circular collar 72 against which an end 74 of a compression spring 76 abuts. The spring 76 includes another end 78 bearing against long leg 44 of bracket 42 and encompasses stem 54 above bracket 42. Another compression spring 80 encompasses stern 54 below bracket 42 and includes a first end 82 bearing against bracket 42 and a second end 84 bearing against piston 62.

The cup is aiiixed to base portion 14 by a clamp 86 comprising a pair of clamping halves 88,` which are affixed to ange 22 by bolt and nut assemblies 92, 94, respectively, and which are maintained in clamping engagement with cup 40 by an adjusting screw 96.

The cup 40 includes a closed bottom wall 98, an encompassing side wall and an open top 102 and is positioned in the path of travel of the piston 62 as it moves from its FIGURE l position to its FIGURE 2 position along the path indicated by arrows 104 in FIG- URE 1. The piston 62 is maintained in substantially airtight relationship with cup 40 by an O-ring or gasket 106 which encompasses piston 62 and forms a friction t with side wall 100.

In its FIGURE 2 position, face 66 of piston 62 lies adjacent bottom wall 98 of cup 40 in fluid communication with a suitable means, generally designated 108, for automatically evacuating air from cup 40 when frame 30 is swung to a clamping position on bottom portion 14 so that atmospheric pressure on upper face 64 of piston 62 will maintain frames 30, 24 and ange 22 in a clamping position.

The evacuating means 108 includes a vacuum pump 110 which is connected to a normally closed valve 112 by a vacuum line 114 and a coupling 116. The valve 112 is connected to the cup 40` by a second vacuum line 118 having a first end connected to valve 112 by a coupling 122 and a second end 124 connected to a T-shaped fitting 126 by a coupling 128. The coupling 126 includes an externally threaded cross-arm 130 having a rst end 132 threadedly engaged in an internally threaded aperture 134 provided in bottom wall 98 and a second end 136 connected to a iirst end 138 of a third vacuum line 140 by a coupling 142. The third vacuum line 140 includes a second end 144 which is placed in tluid communication with base portion 14 through bottom wall V16 by a coupling 146.

The valve 112 is connected to an arm 148 of an L- shaped bracket by a pair of bolts 152, 154 and may be afiixed to base portion 14 by securing an arm 156 of bracket 150 to side wall 18 by a pair of bolts 158, 160. The valve .112 includes a body portion 162 haviag an upper end 164, an intermediate portion 166 and a lower end 168 and is provided with a vertical, throughgoing bore 170 and a horizontal bore 172. The upper end 164 is counterbored to form a recess 174, the lower end 168 is counterbored to form a recess 176 and the intermediate portion 166 is counterbored to form a recess 178. The counterbore 176 is provided with an annular seat 180I against which an annular valve member 182 may seat. The valve member 182 is carried by the lower end 184 of a valve stem 186 extending through bore 170 and having an upper end 188 to which an actuating button 190 is aixed. The valve member 182 is normally seated by a spring 192 which encompasses stem 186 in cavity 174 and which has a first end 194 bearing against button 190 and a second end 196 bearing against a washer 198 seated in recess or cavity 174.

Coupling 122 is threadedly engaged in counterbore 178 for placing the second vacuum line 118 in uid communication with bores 170 and 172 upstream of valve member 182 and coupling 116 is threadedly engaged in counterbore 176 for placing vacuum line 114 in fluid communication with bores 170 and 172 downstream of valve member 182, Button 190 is provided with a pair of vents 200, 202 which are covered by the upper end 164 of body portion 162 when button 190 is depressed to its FIGURE 3 position and which are open to atmosphere when valve member 182 is seated so that air is then free to ilow through vents 200, 202, around stem 186, through bores 170 and 172, through the third vacuum line 118 and fitting 126 into cup 40.

The button 190 is automatically moved to its FIGURE 3 position when clamping frame 30 is closed by a swingable finger 204 which is pivotally connected to frame30 by a bolt and nut assembly 206 and a bracket 208. The finger 204 may be swung to the position shown in broken lines in FIGURE 1 to permit button 190 to move to the broken line position shown in FIGURE 3 under the influence of spring 192, seating valve member 182 and venting cup 40 to atmosphere. This releases piston 62 so that frame 30 may be swung to its FIGURE 1 position. Finger 204 may also be swung to its FIGURE 1 position by rotating it in a clockwise direction, as viewediin FIGURE 1, until it engages a stop member 210 provided on bracket 208.

Operation of the device will be readily understood. Frame 30 and finger 204 may be swung to their FIGURE 1 positions and plastic sheet 28, of a type suitable to use in vacuum molding operations, as will be apparent to those skilled in the art, may be placed on resilient pad 24. Clamping frame 30 may then be swung to a closed position where iiange 34 presses peripheral edge 28 of sheet 26 into firm engagement -with pad 24. Piston 62 will then be disposed within cup 40 and iinger 204 will have depressed button 190 unseating valve 182 permitting vacuum pump 110 to evacuate cup 40 through the second vacuum line 118, bore 172, bore 170, counterbore 176 and vacuum line 114. This creates a negative head between O-ring 106 and bottom wall 98 in cup 40 so that atmospheric pressure on face 64 of piston 62 draws stem 54 downwardly toward bottom wall 98 compressing spring 76 establishing a firm clamping couple between clamping frame 30 and a second clamping frame formed by pad 24 and tiange 22 through bracket 42.

Simultaneously, vacuum pump 110 evacuates base portion 14 of vacuum molding fixture 12 through the third vacuum line 140, T-shaped fitting 126, the second vacuum line 120, valve 112 and vacuum line 114. This draws sheet 26 through open top 20 to the position shown in FIG- URE 2 where sheet 26 is conformed to the shape of a container formed by bottom wall 16, side walls 18 and open top 20.

Finger 204 may then be swung to the broken line position shown in FIGURE 1 so that spring 192 may return button 190 to the position shown in broken lines in FIGURE 3 permitting atmospheric air to enter vents 200, 202 and ow to cup 40 through bores 170, 172, the second vacuum line 118 and T-shaped fitting 126. This equalizes the pressure exerted on piston 62 by subjecting face 66 to atmospheric pressure so that clamping frame 30 may be quickly and easily swung to its FIG- URE 1 position. Finger 204 may then be swung to the position shown in solid lines in FIGURE 1. It will, of course, be apparent to those skilled in the art that finger 204 may be counterbalanced in such a manner that it will automatically swing against stop member 201 when clamping frame 30 is swung to its FIGURE 1 position.

While the particular sheet-clamping couple herein shown and described in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodiment of the invention and that no limitations are intended to the details of construction or design herein shown other than as defined in the appended claims, which form a part of this disclosure.

What is claimed is:

1. A sheet-clamping couple, comprising:

a first clamping frame;

a second clamping frame;

hinge means swingably connecting said frames together;

a piston means attached to one of said frames, said piston means having at least two faces;

cup means iixedly mounted in the path of travel of said piston means for receiving said piston means when one of said frames is swung relative to the other of said frames, said cup means having a closed bottom wall, an encompassing side wall and an open top, said piston means having been adapted to pass through said open top in said cup means, said piston means including means for forming a substantially fluid-tight seal with said side wall of said cup means when one of said faces is positioned adjacent said bottom wall of said cup means and said frames are engaged together during a clamping operation; and lmeans communicating with said cup means for evacuating air therefrom between said sealing means and said bottom wall of said cup means, whereby atmospheric pressure on the other face of said piston means maintains said frames in a clamping position.

2. A couple as stated in claim 1 wherein said evacuating means includes a vacuum pump and a valve means, said valve means being connected to said vacuum pump for controlling iiow of air from said cup means to said pump means, said valve means being normally closed to prevent fiuid flow from said cup means to said pump means and including actuating means for automatically opening said valve means when said frames are engaged together.

3. A couple as stated in claim 2 wherein said actuating means includes a finger carried by one of said frames, said valve means being carried by the other said frames and being engaged by said finger when said frames are engaged together.

4. A couple as stated in claim 3 wherein said finger is pivotally connected to said one frame, whereby said finger may -be swung away from said valve means to take said pump means out of communication with said cup means.

5. A couple as stated in claim 4 wherein said valve means includes means venting said cup means to atmosphere when said valve is closed.

6. A couple as stated in claim 5 wherein said valve means comprises:

a valve body having first and second ends and an intermediate portion;

a first bore extending through said Valve body from one of said ends to the other of said ends;

a second bore provided in said intermediate portion of said valve body in fiuid communication with said first bore;

a first recess provided in said one end of said valve body in communication with said first bore;

a second recess provided in the other end of said valve body in communication with said irst bore;

a valve seat provided in said second recess;

a valve member reciprocally mounted in said first bor in operative association with said valve seat for seating thereon in one position of operation of said valve means, `said valve member including a valve stem extending from said valve seat to said first recess;

a valve-actuating button afiixed to said stem in said first recess, said button being provided with vent means open to atmosphere when said button is in one position of operation wherein said valve member is seated on said seat, said vent means being in fiuid communication with lirst bore and said second bore when said Valve member is seated; and

spring means provided in said first recess in operative association with said valve-actuating button for biasing said valve member to a normally seated position.

7. A couple as stated in claim 6 wherein said first clamping frame comprises a swingable frame on a vacuum molding fixture and said second clamping frame comprises a base portion for said iixture, said piston means being attached to said swingable frame and said cup means being attached to said base portion.

References Cited UNITED STATES PATENTS 2,441,097 5/ 1948 Hicks. 2,694,227 11/ 1954 Fordyce et al. 2,991,600 7/ 1961 Lancaster.

ROBERT C. RIORDON, Primary Examiner U.S. Cl. X.R. 1\8-19; 264-90 

